Production of hollow ingots



Dec. 5, 1933. E. F. JONES PRODUCTION OF HOLLOW INGOTS Filed Dec. 13, 1932 A awwwwmwvvj a R I m "and w 2 l WW\\ 1r rue! Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE.

Application December 13, 1932, Serial No. 647,050, and in Great Britain December 29, 1931 1 Claim.

The present invention relates to the production of hollow metal ingots for use, more particularly, in the manufacture of metal tubes and hollow bars, such as drill-steel, shafts and the In a known process of making hollow metal ingots a plunger is introduced axially into a mould partially filled with molten metal, or metal which is still plastic, or at least has a sublo stantial liquid or plastic core, so that the molten or plastic metal is brought to the form the desired hollow ingot. After the metal has solidirled suficiently to sustain itself the plunger is withdrawn.

It has been proposed to place the metal under pressure in the mould by providing the plunger with an enlarged portion adapted to fit the mouth of the mould, or by providing the mould with a cover fitting closely round the plunger.

According to the present invention, alterthe plunger has been introduced into the partially -filled mould the motion, or" the plunger into the mould is stopped and pressure is applied to surface or" the metal between the lateral sure face of the plunger and the walls of the mould and is maintained until the ingot is sufllciently solidified to sustain itself, the pressure then being released, the plunger withdrawn from the ingot and the latter ejected from the mould.

The hollow ingot thus produced can then be subjected to any desired extension treatment to convert it into a tube. Under suitable plant conditions the extension can be effected with little or no additional heating of the ingot other than that which may be necessary for soaking it.

The invention also comprises apparatus for carrying out the improved process, in which a boiler is provided fitting, around the axially mova able plunger and within the mould mouth and adapted to be moved independently oi the plunger to'exert pressure on the metal in the mould.

In an apparatus comprising a mould and a core adapted to be located in the mould priorto the introduction or the metal into the mould,

it is known to provide a collar fitting around the.

core and within the mould mouth and adapted to be moved to exert pressure on the metal in the mould.

The present invention also comprises certain other improvements in the process and appa-- ratus which will be more fully described with reference to the accompanying drawing, in

Figures I to III are diagrammatic views illustrating stages of the operation; and

Figures IV and V are similar views illustrating a modified procedure.

For carrying out the invention there is provided an ingot mould 2 adapted to be brought into a position where a plunger is to be introduced and removed therefrom.

At the said position is provided a plunger 3 adapted to be moved up and down on theaxis of the mould when the latter is in the said position.

There is also provided a collar l through which the plunger works and which can itself be raised and forcibly lowered. The collar fits .the plunger and the mouth of the mould sufficiently closely to prevent liquid metal from passing it. The plunger is hollow and provided with a pipe 5 for circulating cooling fluid through it at a controlled rate.

In the first step of the process the mould is partly filled with liquid metal 6 and is brought, as shown in Figure I, under the raised plunger and collar. The collar is lowered into the mouth of the mould, as shown in Figure II and there held stationary, forming a cover for the mould and a guide for the plunger 3.

The plunger is then moved downward into the molten metal. It is brought to the bottom of the mould if an ingot open at both ends is required; or is stopped as shown in Figure 11 to produce the bottle form of ingot required for the production of a tube on a push bench. By this operation the molten metal is displaced so that it substantially fills the mould, as indicated at 6, the quantity originally poured being calculated with that object.

In the next operation the collar is forced downward as indicated by the dotted lines in Figure H to put the molten metal under heavy pressure with the object of ensuring dense metal in the completed ingot. The pressure is maintained while the metal solidifies sufiiciently to maintain its form, the collar followingthe metal down as it shrinks during solidification. 100 The plunger 3 tapers as shown in the drawing from a smaller diameter at the bottom to a larger diameter at the top in order to permit it to be ultimately withdrawn from the ingot. As the metal solidifies and as the collar 4 follows it 105 down, the movement of the metal is continuously in the direction in which the plunger is reduced in diameter; Thus during the initial contraction of the metal cracking is avoided.

Immediately the ingot metal has solidified 1 10 sufiiciently to maintain its form, the plunger is withdrawn as seen in Figure 111. Prompt removal of the plunger, as soon as the ingot metal can maintain itself and has suflered the minimum-of contraction, is important not only to enable the plunger to be released but to prevent cracking of the metal. The withdrawal of the plunger permits the metal to continue to contract without cracking. At the same time that withdrawal of the plunger starts, pressure is removed from the collar, but the latter remains in position and acts as'a stripper to hold the ingot 6 in the mould and thereby strip it from the plunger.

Also at about the moment of the withdrawal of the plunger a rapid circulation of cooling fluid is set up in the plunger, so as to cool it and cause it to contract and thereby to facilitate its detachment from the ingot metal.

' Thereafter the collar is raised, the mould is moved from the plunging position and the ingot is ejected from it. The ingot is subjected, preferably without re-heating but after a heat soaking treatment if desired, to any desired operation to form it into a tube. It may for instance be rolled, drawn or pushed through dies according to well known methods.

The lower face of the collar is preferably concaved in cross section in order to round the rim of the open end of the ingot, as is desirable for tube making purposes. The present process, in which the pressure is applied to the surface of the metal between the lateral surface of the plunger and the walls of the mould, is distinguished from any arrangement in which pressure is applied to the bottom of the metal, because in the latter case the movement of the metal during solidification would be upwards, that is, in the direction in which the plunger increases in diameter. Thus contraction of the cooling metal is opposed and cracking of the ingot may result.

According to a further feature of the invention the hollow ingot is provided with a lining of different material such as non-corroding metal, by the .method illustrated in Figures IV and V.

According to this method a line tube 7 is frictionally retained on the plunger below the collar 4. Such tube is carried by the plunger into the molten metal 6 and is left in the ingot 6 as shown in Figure V. It would usually be such as to weld with the ingot metal; and, in any case, its detachment from the plunger is ensured by the stripping action of the collar 4. A layer 8 of material of low heat conductivity, for example asbestos, may be inserted between the plunger and the tube 7 to minimize cooling of the tube when the plunger is cooled to contract it as above described.

I claim:-

The process of making hollow metal iri'gots which consists in partly filling a mould with molten metal, positioning the partially filled mould in register with a plunger and pressure member, introducing the pressure member into the mouth of the mould, introducing the plunger axially into the mould under the guidance of the pressure member and thereby bringing the molten metal to the form of a hollow ingot, stopping the motion of the plunger into the mould, moving said pressure member between the lateral surface of the plunger and the walls of the mould to apply pressure to the molten metal, maintaining said pressure until the ingot is sufficiently solidified to sustain itself, then withdrawing the plunger from the ingot and the mould, and thereafter withdrawing the pressure member from the mould.

ERNEST FRASER JONES. 

